Fretted instrument sounding board process and product



e 10,, 1970 R. s. JONES, SR 3,494,241

FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1, 19675 Sheets-Sheet 1 BY semmes $2 semmes ATTORNEYS Feb. 10, 1970 R. s.JQNES, SR 3,494,241

FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1, 19675 Sheets-Sheet 2 INVENTOR flay/Av 5. 74/2255? BY Semmes $2 SemmesATTORNEY Feb. 10, 1970 R 5, ES, 5R 3,494,241

FRETTED INSTRUMENT SOUNDING BOARD PROCESS AND PRODUCT Filed Nov. 1. 19675 Sheets-Sheet 3 I F/a x 76? y INVENTOR Iii/47s 74022:, 5/9:

81! Se'mmes & 8mm

ATTORNEYS United States Patent 3,494,241 FRETTED INSTRUMENT SOUNDINGBOARD PROCESS AND PRODUCT Ralph S. Jones, Sr., Hyattstown, Md. 20734Filed Nov. 1, 1967, Ser. No. 679,897 Int. Cl. Gd 3/02 U.S. Cl. 84-307 2Claims ABSTRACT OF THE DISCLOSURE In the art of fretted and bowedmusical instruments, an effort is made herein to provide, in woodeninstruments, resonance and volume with clear tone and power whereby tocarry the sound created at greater distances without distortion or lossof tone quality. The process in its most explicit terms resides incircularly shaping correspondng boards to delineate opposed circulardiaphragms which are of exquisite uniformity from circumference tocenter thereof, the uniformity of thicknesses resulting in precisionquality control in the manufacture of corresponding instruments. Theinstrument when assembled provides hereby an oval shaped air chamber.

Description of the prior art In the prior art, the design and shape ofthe diaphragm forming the sounding board varies with the exteriorpattern of each instrument, most such instruments having been made ofvery thin selected woods having proven volume characteristics and giveninterior bracing, sufficient to support the thin structure against thestress of string tension. In such instruments, variation in depth ofacoustic chamber yields progressively deeper or higher pitchedtones, asis known. Among the more popular instruments are those having archedtops and backs which are generally considered thicker in the centeradjacent the bridge area tapering to the outer edge, thus yieldingimproved tone resonance and power, the arch created by the constructionproviding thereby an oval shaped air chamber. Conventionally, soundposts have been provided contiguous the bridge to transmit vibrationsfrom front to back, Whereas others rely upon air transmission and yet inthe manufacture of succeeding instruments purporting to have the samequalities, uniform tolerances as between diaphragm elements becomespractically impossible. Moreover, such instrumentation does not lenditself to variation in ovenall pattern or design of the instrumentand/or improved acoustics brought about by variation in exterior design.Additionally, cracking and warping are brought about by the angularrelation of supporting woods to supported, where imperfect sealingoccurs or as inordinate stresses may be applied.

Field of the invention The field of the invention is such as toencompass both acoustic and acoustic-electric or electronic frettedinstruments as well as bowed musical instruments, wherein uniformity inthe creation of the acoustic chamber is of importance in the manufactureof multiple instruments each having the same precision quality controlin the transmission of energy from the string. An effort is made hereinto maintain the natural frequency of the instrument low, as for exampleonly, under 360 c.p.s. avoiding thereby the range of harmonicfrequencies which ultimately yield feedback, currently prevalent inelectronic and electric instrument.

Description of the drawings In the drawings: FIGURE 1 is a plan viewshowing one-half of a circular, diaphragm sounding board acousticchamber prepared in accordance with the first step of manufacturethereof;

FIGURE 2 is a vertical sectional view of the invention shown in FIGURE1, taken along the lines 2-2 of FIG- URE 1;

FIGURE 3 is a showing of corresponding halves manufactured initially inaccordance with the FIGURE 1 and FIGURE 2 showings, whereby the finalstep of shaping the respective opposed sounding boards has been applied;

FIGURE 4 is a modification of invention whereby the two assembled halvescontaining the sounding board of a fretted instrument have been shapedinitially in accordance with the principles established under FIG- URES1 and 2 inclusive and finished in accordance with the principlesillustrated in FIGURE 3;

FIGURE 5 is a sectional view of invention showing enlarged portions ofthe respective sounding boards of FIGURE 1 in the pre-assembledcondition;

FIGURE 6 is a view of the means for securing shown in FIGURE 5, fullyassembled;

FIGURE 7 is a plan view of the assembled FIGURE 3 modification showingstring anchor and individual bridges set in place; and

FIGURE 8 is a vertical sectional View of the FIGURE 7 device taken alongthe lines 88 thereof.

Description of invention To yield better tone and preserve the power ofthe energy created by string vibration and to maintain the naturalfrequency of the instrument low are among the objectives of invention.These are achieved by tapering the diaphragm sounding board elements,yielding a controlled tone, power of resonance and changing of frequencyfrom center to rim of the respective diaphragms. Naturally, varyingthicknesses of diaphragm will be used according to the density of theparticular wood employed in the manufacture of the instrument, toachieve precision quality control, from instrument to instrument, toavoid feedback, to maintain natural frequency low, to preserve power ofresonance, and to control tone. The instruments shown herein (FIGS. 1-6inclusive) are especially adapted to electric-acoustic systems;nonetheless, it will be appreciated that for plain acoustic use, soundholes shall be appropriately cut in the top, back or rim of theinstrument. Moreover, whereas the showings herein involve two-piecediaphragm construction to comprise the entire body of the instrumentwith rim, the application of separate rim with either front and/or backdiaphragm attached thereto is within the spirit of the invention.

The process and product involve the steps illustrated in FIGS. 1-3inclusive wherein it Will be noted with respect to FIG. 1 that a solidblank of material 100, configured to external design requirement hasbeen placed on a lathe and accurately centered whereby the instrumenthalf having fret board base 112, interior surface 114 and lockinggrooves 116 defines as well the outer surface 118. By graduated lathingthe surfaces of the diaphragm 120, 122, 124, 126 and 128 are formedprogressing in thickness from the center of the diaphragm to the outerrim thereof. In finishing by rotary shaving or sanding, one provides thediaphragm surfaces 140 and 140' of FIG. 3 wherein the halves and 120'have been assembled. My micrometric setting of the cutting tool of thelathe, a duplication of the same instrument may be made substantiallyautomatically and without resort to fallibility of human error. In theparticular FIG. 3 construction, the circular diaphragm sounding boardscomprising the acoustic chamber are of convex configuration, the opposedand thickest surfaces of the respective sounding boards 118 and 118'providing a suitable base for a sound post, not shown.

A related arched top and back construction is shown in FIG. 4 whereinthe modification 200 is provided with convex surfaces 240 and 240"yielding a substantially stronger acoustic chamber than is provided inthe FIGS. 1 and 3 concepts. Obviously, different thicknesses ofdiaphragms will be used according to the density of the particular wood,conforming thereby to a pre-selected frequency, established byelectronic visual testing at interval diameters of the diaphragm tocontrol thereby tone, power of resonance and frequency change fromcenter to rim.

In assembly, it is proposed that the diaphragm half is circularlymachined of the varying thicknesses and finished by shaving and sandingas indicated; that subsequently, the machine diaphragms are respectivelytreated with a moisture resistant lacquer both externally and internallyof the respective surfaces and that sequentially, the two halves arebrought together under spring tension in the manner illustrated in FIGS.5 and 6 by means of the opposed spring tension assemblies 150 and 150which are fastened to the instrument halves 110 and 110' by means of thescrews 152 and locked in position as in FIG. 6. This fastenerconstruction is a tension type yielding a vibration free overallconstruction.

The results achieved hereby are to avoid cracking of joints as betweenthe components forming the diaphragm sounding boards, which may be dueto expansion and contraction of counteracting grains in the wood.Accordingly, in practice, it is desired that the respective halvesdelineating the acoustic chamber are aligned grain for grain, precedentto tension locking thereof.

This controlled thickness controls feedback and yields perfectreproduction with uniform response in view of the asymmetric formationof the respective halves comprising the sounding board and of theopportunity to duplicate same faithfully from instrument to instrumentdepending on the setting of the machine tools involved.

With reference now to FIGS. 7 and 8, the instrument having top isprovided with suitable string anchor 150, the respective strings beinganchored by posts 152, said strings being adapted to pass overindividual bridges mounted as indicated at upon a transversely extendingbase 162462 through which the respective adjustable uprights 164- havingadjustment nut 166 with bevelled edge 168 is seated to secure therearmost bifurcated portion of the respective string bridges '170. Thebridges 170 are, as indicated in FIG. 7,' bifurcated at 172 and providedwith transverse corrugations 174, for seating with the bevelled edge 168of the adjustment nut 166. At the forward portion of each cantileverbridge construction 170- there is found the bridge slope 176 havingappropriate grooves 178 disposed for securing each string againsttransverse displacement. Said bridge includes cavity 180 havingappropriate corrugations to securely seat the bevelled edge 182 of thefulcrum member 184, said fulcrum member being movably adjustablelongitudinally of the instrument and vertically to Vary the pitch of therespective strings in critical sounding board area which is normallylocated immediately adjacent the center of the sounding board, per se.

I claim:

1. In fretted musical instruments having strings secured in adjustablerelation to a diaphragm sounding board, the improvement comprising:

(A) a floating bridge for at least one of each of said strings;

(B) a bridge anchor secured to the diaphragm of the sounding board, saidbridge being in movable contact with the bridge anchor at one end andhaving a string supporting projection at the other end,

(C) a movable bridge fulcrum on the diaphragm detached from the bridge,the point of maximum string tension support being regulated by thefulcrum location on the diaphragm, intermediate ends of the bridge.

2. The improvement according to claim 1 in which the fulcrum member isdisposed substantially immediately adjacent the center of the diaphragmfor horizontal adjustment relative thereto and for vertical adjustmentof the cantilever bridge to increase and decrease the pressure on thediaphragm as the increase in string tension may be adjusted.

References fited UNITED STATES PATENTS 906,612 12/1908 Cayton 84-2911,001,302 8/1911 Ranch 84-291 1,361,182 12/1920 Reams et al. 84-2911,649,559 11/1927 Bacon 84-291 3,181,409 5/1965 Burns et al 84-3073,302,507 2/1967 Fender 84-291 OTHER REFERENCES Music Trade Review, Oct.8, 1921.

RICHARD B. WILKINSON, Primary Examiner L. R. FRANKLIN, AssistantExaminer US. Cl. X.R. 84-291, 294

